CM850 Electronic Control System – FAULT CODE 221

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Overview

Barometric Pressure Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The barometric pressure sensor is used by the ECM to monitor the barometric pressure. This value is one of many inputs used by the ECM to determine the correct air/fuel ratio for proper engine operation.

Component Location

The barometric pressure sensor is mounted on the main branch of the engine harness near the ECM. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.

Shop Talk

The barometric pressure sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting Fault Code 221, check for multiple faults.

Possible causes of this fault code include:

• Open return circuit in the harness, connectors, or sensor
• Signal circuit shorted to sensor supply or battery voltage.

Operation below sea level:

• Note: If you have equipment that operates below sea level (such as in a mining operation) and your equipment continues to log Fault Code 221, contact Cummins® Service Engineering for the correct calibration.

On-Board Diagnostics (OBD) Information (Euro 4 Certified Engines):

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• The ECM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. The MIL lamp and fault code can also be cleared using the INSITE™ electronic service tool.
• The fault code will be cleared from memory after 40 consecutive drive cycles where the diagnostic runs and passes.

On-Board Diagnostics (OBD) Information (Euro 4 Stage 1+ Certified Engines):

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• An engine torque derate will be activated after 50 hours of engine operation with the fault code active.
• The ECM turns OFF the malfunction indicator lamp (MIL) after 1 ignition cycle that the diagnostic runs and does not fail. The MIL lamp cannot be cleared using the INSITE™ electronic service tool.
• The fault code will be cleared from memory after 400 days or 9600 hours of engine operation.

Refer to Troubleshooting Fault Code t05-221